1. Field of the Invention
The present invention relates to a structure for standardizing parts of a roller assembly for a construction vehicle, which can be used for the same size of construction vehicles having different structural specifications of a plurality of construction vehicle makers.
2. Description of Related Art
As disclosed in Japanese Patent Publication 2000-159159 and as illustrated in FIGS. 5 and 6, a roller assembly for a construction vehicle mounted to an endless track generally includes a shell 1, a shaft 2, a floating seal 3, a bushing 4 and a collar 5 as parts.
The shell 1 is a part which directly contacts a link of the endless track. The shell 1 is manufactured by forging or casting material, rough-machining the material, welding or pressure-welding the materials, heat-treating the material, and finish-machining the material into a final part.
The shaft 2 is an axis part about which the shell 1 rotates. The shaft 2 is manufactured by cutting a rolled bar having a circular cross section, rough-machining the bar, forming a hole in the bar by drilling, heat-treating the bar, and finish-machining the bar into a final part.
The roller assembly is lubricated by oil so that the shell 1 can smoothly rotate about the shaft 2. The floating seal 3 is a part for preventing lubricating oil from leaking much outside at a contacting surface between the shaft 2 and the shell 1 during relative rotation.
The bushing 4 is a part acting as a bearing metal.
The collar 5 is a part for fixing the roller assembly to a track frame. The collar 5 is manufactured usually by forging or casting a material, and finish-machining the material into a final part. The collar 5 may be manufactured by machining a rolled rod.
The structural specification for each part of the roller assembly is different among the construction vehicles manufactured by different construction vehicle makers, even if the size of the construction vehicles is the same among five sizes of construction vehicles, including a super-large size, a large size, a middle size, a small size, and a super-small size.
When the size of the construction vehicle changes, the configuration and the dimension of each part of the roller assembly also change according to the change in size of the construction vehicle.
When the endless track maker manufactures roller assemblies for the same size of construction vehicles of different construction vehicle makers, the roller maker has to manufacture shells, shafts, floating seals, bushings and collars that can be used only for the corresponding construction vehicles of each construction vehicle maker. Since the configurations and dimensions of the roller assemblies change according to a change in size of the construction vehicle, for each roller part (the shell 1, the shaft 2, the floating seal 3, the bushing 4, and the collar 5) the roller maker has to manufacture a large number (the number of the construction vehicle makers×the number (five) of the sizes of the construction vehicles) of kinds of parts. As a result, the number of the kinds of the parts is very large, and a reduction in cost due to mass production has been difficult to achieve.